1. Field of the Invention
This invention relates to the treatment of particulate matter collected, for example, pursuant to an environmental air quality control requirement. Disposal of the particulate may be more readily accomplished by separating the particulate into portions having different physical and chemical characteristics.
2. Description of the Prior Art
Leaching whereby a substance is subjected to a flow of liquid to remove a soluble portion of the substance is well known. One example in years past is wood ashes being leached with water to produce lye, i.e. a strong, alkaline solution. The lye was then used to make soap.
Leaching has also proved to be valuable in processing baghouse dust collected pursuant to environmental air quality control requirements applicable to a galvanizing process. This dust or particulate contains proximately 50 percent insoluble aluminum and zinc oxides which are nontoxic. A remainder of the dust is toxic being primarily soluble aluminum, zinc and ammonia chlorides. The insoluble portion being nontoxic could be disposed of as a landfill while the soluble portion reused in the formation of galvanizing fluxes.
One method of separating the soluble and insoluble portions is the use of vacuum filtration after the dust and water are countercurrently mixed in two to five stages.